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Show 368 MOLLUSCA. CALYPTR.tEA, Lam. We observe a conical shell, in the hollow of which is a little lamina that projects inwards, resembling the commencement of a columella, and that interposes itself between a fold of the abdominal sac. The branchire are composed of a range of numerous filaments, long and slender, like hairs. In some of them this lamina adheres to the bottom of the cone, being itself bent into a portion of a cone or of a tube, and descend-ing vertically( 1 ). In others it is almost horizontal, and adheres to the sides of the cone, which is marked above by a spiral line that establishes some relation between their shell and that of a Trochus(2). SIPHONARIA, Sowerby. The shell of the Siphonarire, which have been recently separated from the Patellre, at the first glance seems very similar to a flattened Patella, with radiating sulci; but its margin projects rather more on the right side, and it is excavated beneath by a slight furrow, which terminates at this prominence of the margin, to which there is a corresponding lateral hole in the mantle, for the introduction of water into the branchial cavity, placed on the back, that is closed on every other point. The respiratory organ consists of a few small lamellre, arranged in one transverse line on the roof of that cavity; the tentacula seem to be wanting, the head being merely furnished with a narrow veil( 3 ). There are some species, in which even this slight appearance of the canal, in the shell, is effaced, resembling in toto that of a Patella, except in its summit, which is behind( 4). In the SIGARETus, Adans. The shell is flattened, its aperture ample and round, and the spire (1) Patella eque!Jtria, L., List., 546-38;-Pat. sinensis, lb., 39;-Pat. trochi· formis, Martini, I, xiii, 135;-Pat. auricula, Chemn., X, clxviii, 1628-29;-Pat. plicata, Nat. Forsch., XVHI, 11, 12;-Pat. striata, lb., 13. ~~) .!'atella contorta, Nat. Forsch., IX, iii, 34, VITI, 11-14;-Pat. depres3a, lb., xvm, u, 11. ~3) Patella sipho;-Siplwnovia concinna, Sowerb., Gen. of Shells, No. XXI;-S. ex~gua, Id:, lb. See Savigny, Dcscr. de l'Eg., Zool. Gaster., pl. iii, f. 3, and Coq., pl. 1, f: 1. Some years ago M. Gray proposed a genus G.ADINIA, (Philos. Magaz., Aprll1824) which is precisely the same as Sll'HONAnu.. (4) Siphonaria tristentis, Sowerb., loc. cit. GASTEROPODA PECTINIBRANCHIAT A. 369 very moderate, its whorls rapidly enlarging and seen within, but concealed during the life of the animal in the thickness of a fungous shield, which projects considerably beyond it, as well as the foot, and which is the true mantle. Before this mantle are an emargina· tion and a semi-canal, which serve to conduct water into the branchial cavity, and which form the passage to the following family, but of which there are no impressions on the shell. The tentacula are conical, with the eyes at their external base; the penis of the male is very large. Some species are found on the coast of France. The CoRIOCELLA, Blainv., Consists of Sigareti, the shell of which is horny and almost membranous, like that of the Aplysire( l ). CRYPTOSTOMA, Blainv. The shell, resembling that of a Sigaretus, with the head and abdomen, which it covers, supported by a foot four times its size, cut square behind, and forming before a fleshy, oblong bundle that constitutes nearly one-half of its mass. The animal has a flat head, two tentacula, a broad branchial pecten on the roof of its dorsal cavity, and a penis under the right tentaculum; but I can find no emargina-tion in the mantle(2). FAMILY III. BUCCINO IDA. This family has a spiral shell, in the aperture of which, near the extremity of the columella, is an emargination or a canal for transmitting the siphon or tube, which is itself but an elon· gated fold of the mantle. The greater or less length of the canal, when there is one, the size of the aperture, and the (1) The Coriocelle noire, Blainv., Malac., XLII, f. 1. This animal is not de· prived of a shell, as the author of the genus imagined, but it is thin and flexible. (2) Besides the species in the British Museum (Cr. Leacltii, Blainv. Malac., XLII, 3), we have one (Cr. carolinum, Cuv.) sent from Carolina by M. L'Hermi· nier. VoL. Il.-2 W |